Acidified milk beverages are very popular today as they offer simultaneously sweetness and freshness to consumers. These beverages further provide well known milk nutrients like proteins or minerals and, when acidity is achieved by means of fruits juices, the latter further bring flavours or vitamins in addition to the mere acidifying effect.
Most of the acidified milk based beverages are available today as “ready-to-drink” beverages, which require storage at refrigerated conditions and, consequently, which have a limited shelf life. Several attempts have been made in the past to increase stability and storage period of said “ready-to-drink” beverages, e.g. by controlling pH with suitable stabilizers, increasing sugar content or removal of undesired components like certain milk or juice electrolytes (see e.g. U.S. Pat. No. 4,676,988).
U.S. Pat. No. 3,800,052 discloses the preparation of a sour, “ready-to-drink” milk beverage having a good whiteness and stability made by adding acid to skim milk to bring the pH of the beverage within the range of 3.5 to 3.7. Acid is added to skim milk and water in predetermined proportions, then sugar and the whole is subject to moderate heating (around 70° C.), refined and flavoured if necessary and eventually bottled as is for storage or for direct consumption.
U.S. Pat. No. 4,194,019 describes a method for preparing an acidified milk beverage which has milk protein stably dispersed therein and which is “ready-to-drink” without dilution, when subjecting an acidified skimmed milk having a milk solid-not-fat (SNF) content of 0.5 to 3.5 weight % and a pH value of 3.0 to 3.9 to heat treatment at ultra-high temperature. Acidic pH is due to lactic fermentation and addition of sugar is optional.
U.S. Pat. No. 4,192,901 eventually discloses a method for manufacturing a concentrate defined as “milk-containing acid syrup” which is further used for preparing beverages by dilution with water. In this case, the inventors have addressed a specific issue, i.e. the stabilization of milk proteins by monitoring the casein I sugar ratio and subsequently subjecting the acidified milk-sugar mixture to ultra-high temperature heating: inventors have assumed that during said ultra-high temperature heat treatment, casein undergoes some form of reaction with sugar and, hydrophilic property of the casein is significantly enhanced.
Beverage dispensing machines or visual bowls are also quite popular in modem communities so they are frequently used for dispensing various kinds of beverages in cans or even as freshly prepared fruits juices or similar beverages. When refrigerated conditions like those which should apply to “ready-to-drink” milk based beverages are necessary, this is leading to use complex and expensive techniques or machines. Further, when working with milk based beverages hygiene is a critical factor.
An approach would be to allow preparation of such acidified milk based beverages immediately before consumption, for instance by storing separately sensitive or non compatible components like e.g. milk and acid or fruit juice and then mix them on demand. This way proved in fact unduly complex and expensive and, also, not suitable for use in conventional beverage dispensing machines.
An other way to by-pass the above difficulties or drawbacks would be using stable concentrated base compositions which would simply be diluted with water on demand, i.e. just before consumption. The art, unfortunately, does not provide today any appropriate solution to the skilled artisan.